This study is designed to investigate the aerodynamic characteristics of the upper vocal tract in 520 normally speaking subjects and between 300 and 500 subjects with palatal clefts ranging in age from five to 29 years. Data on the size of the velopharyngeal orifice and pressure-flow timing characteristics during speech production will be collected along with measurements of pharyngeal-nasal airway resistance and oral-nasal breathing ratios. Normal children will be studied longitudinally during the period of adenoid atrophy. Children with cleft palates who exhibit borderline speech characteristics or who have pharyngeal flaps during the course of the study also will be followed longitudinally over time. Measurements of the speakers with and without clefts will be compared at the different ages, and the changes occurring as a function of age will be evaluated. This study represents the first large-scale comparative investigation of aerodynamic characteristics from early childhood through adulthood in speakers without palatal clefts as they compare to speakers with clefts and the first study to assess aerodynamic changes over time in cleft speakers. These data are vital to improving our criteria for the clinical interpretation of aerodynamic measurements leading to decisions about clinical management. The longitudinal data, in particular, should be of special value to speech clinicians and surgeons in determining the type and timing of treatment. Finally, insights relative to the effects of normal growth and to adaptations of cleft lip and palate speakers with marginal or impaired speech with or without pharyngeal flaps will be obtained.